It is highly important for water conservancy project to detect the hidden trouble of the underwater structures. However, traditional sonar system and underwater visualization tools exist some defects when they are used alone.Three-dimensional real-time imaging sonar system get over the disadvantages of the traditional mode efficiently. It has the following features: real-time, clear image, 3D imaging techniques, and it could work in zero visibility water(muddy water) and other complex water enverionments.The result of the acceptance test and preliminary application of 3D sonar equipment showed a stable integral performance. Each technology index of the equipment showed that it could meet the demand for detecting the underwater structures of water conservancy project. It provide crucial technical method for quickly, efficiently and scientifically detecting levee, embankment and other underwater structures of water conservancy